826 resultados para 12930-064
Resumo:
The sensitivity of the tropics to climate change, particularly the amplitude of glacial-to-interglacial changes in sea surface temperature (SST), is one of the great controversies in paleoclimatology. Here we reassess faunal estimates of ice age SSTs, focusing on the problem of no-analog planktonic foraminiferal assemblages in the equatorial oceans that confounds both classical transfer function and modern analog methods. A new calibration strategy developed here, which uses past variability of species to define robust faunal assemblages, solves the no-analog problem and reveals ice age cooling of 5° to 6°C in the equatorial current systems of the Atlantic and eastern Pacific Oceans. Classical transfer functions underestimated temperature changes in some areas of the tropical oceans because core-top assemblages misrepresented the ice age faunal assemblages. Our finding is consistent with some geochemical estimates and model predictions of greater ice age cooling in the tropics than was inferred by Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) [1981] and thus may help to resolve a long-standing controversy. Our new foraminiferal transfer function suggests that such cooling was limited to the equatorial current systems, however, and supports CLIMAP's inference of stability of the subtropical gyre centers.
Resumo:
The need for universal access to health and the failure of the pedagogical model centered on the transmission of knowledge has led to changes in the training of health professionals. The objective of this study was to provide a new alternative for evaluating dental students through the development, validation and application of evaluation criteria based on the National Curriculum Guidelines (DCN in Brazil). Therefore, the study was conducted in three phases: development and validation of evaluation criteria of Dentistry courses based on the DCN; a pilot study to verify the applicability of the validated criteria and evaluation of the dentistry courses in the Northeast. In the first stage, a logical model was formulated, allowing for the construction of a criteria matrix, validated by a modified Delphi consensus technique. The validated matrix has the following dimensions: Profile of graduates, health care guidance, teaching and service integration, and pedagogical approach. The pilot study was conducted in five dental courses through a documentary study of the pedagogical project course (PPC), and application of validated questionnaires and interviews with course coordinators. The results of the pilot study indicate the possibility of being verified by means of validated criteria and using different methodological proposals, advances and curricular limitations facing the proposed reorientation of training recommended by DCN. The evaluation of Northeast Dentistry courses was carried out by applying a questionnaire validating a matrix of 30 course coordinators, including public and private institutions. The data were submitted to descriptive analysis, and also tested the difference between means and the correlation between the assessment of the coordinators in the dimensions and sub-dimensions with each other, among the general evaluation of courses and between the following variables: administrative category, time since last curriculum updating, participation in reorienting the training of health professionals programs, ENADE and CPC (Preliminary Concepts of the Course) scores in the year 2013. Positive correlation (p <0.01) was found between the means obtained by the perception of the coordinators in most dimensions, and also between them and the overall performance of the course. There were no significant differences between the coordinators’ perception about course performance and the administrative category (public / private). This difference is slightly higher when the average performance is compared with respect to time due to the last curriculum update, getting better performance in courses with the latest updated curriculum, even with there not 11 being this significant difference between dimensions. Better averages of performance were obtained in courses that do not participate in reorientation programs of professional training, with a significant difference (p<0.05) for the overall score and for all dimensions except the dimensions of teaching-service Integration (p = 0.064). There was no significant correlation between the assessment of coordinators in all dimensions, in the overall assessment or ENADE and CPC scores in 2013. The final instrument proposed in this study is a different alternative assessment for health training of both dentists and other professionals, considering that the DCN providing for the training and graduation of professionals is focused on the health needs of the population, integrated with the SUS (the National Brazilian Health System) and based on student-centered learning.
Resumo:
The purpose of this volume, the tenth in a series of similar publications (Goodell, 1964, 1965, 1968; Frakes 1971, 1973 ; Cassidy et al., 1977), is to continue a presentation to the research community of sediment core descriptions and attendant data of cored and otherwise obtained sediments retrieved in waters of the Southern Ocean aboard the research vessel, ARA Islas Orcadas (formerly, USNS Eltanin), as a part of the circumpolar survey begun by Eltanin in 1962 (see issue of Antarctic Journal of the United States, Vol. 8, No. 3, 1973). The data presented herein are concerned with the results of coring activities aboard cruise 1578 of Islas Orcadas, the fourth marine geology coring cruise of this vessel under the terms of the present United States-Argentine agreement. The core descriptions are organised as follows: 1) a brief summary of the coring objectives of the cruise, together with a discussion of core recovery; 2) a table and map of station location data for materials retrieved; 3) a table of tentative age-dates for each piston core; 4) an explanation of the laboratory procedures and descriptive criteria used in the description of the sediments, and 5) lithologic descriptions of the piston and trigger cores, and the piston and trigger core bag samples.
Resumo:
A set of 114 samples from the sediment surface of the Atlantic, eastern Pacific and western Indian sectors of the Southern Ocean has been analyzed for 230Th and biogenic silica. Maps of opal content, Th-normalized mass flux, and Th-normalized biogenic opal flux into the sediment have been derived. Significant differences in sedimentation patterns between the regions can be detected. The mean bulk vertical fluxes integrated into the sediment in the open Southern Ocean are found in a narrow range from 2.9 g/m**2 yr (Eastern Weddell Gyre) to 15.8 g/m**2 yr (Indian sector), setting upper and lower limits to the vertically received fraction of open ocean sediments. The silica flux to sediments of the Atlantic sector of the Southern Ocean is found to be 4.2 ± 1.4 * 10**11 mol/yr, just one half of the last estimate. This adjustment represents 6% of the output term in the global marine silica budget.
Resumo:
We analyzed hydrographic data from the northwestern Weddell Sea continental shelf of the three austral winters 1989, 1997, and 2006 and two summers following the last winter cruise. During summer a thermal front exists at ~64° S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data from the shallow shelf off the tip of the Antarctic Peninsula, spanning a period of 17 yr, shows a salinity decrease of 0.09 for the whole water column, which has a residence time of <1 yr. We interpret this freshening as being caused by a combination of reduced salt input due to a southward sea ice retreat and higher precipitation during the late 20th century on the western Weddell Sea continental shelf. However, less salinification might also result from a delicate interplay between enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves and increased Larsen C ice loss.